This study confirms previous reports on the location of the two components of the cardiac plexus. This study records the thoracic caudal limit of the sympathetic contributions to the cardiac plexus as the T5 ganglion.
LIST OF TABLES
LIST OF PLATES
EMBRYOLOGY
- EMBRYOLOGY OF THE PERIPHERAL NERVOUS SYSTEM
- EMBRYOLOGY OF THE AUTONOMIC NERVOUS SYSTEM
- EMBRYOLOGY OF THE SYMPATHETIC NERVOUS SYSTEM AND GANGLIA
- EMBRYOLOGY OF PARASYMPATHETIC NERVOUS SYSTEM AND GANGLIA
- DEVELOPMENT OF THE NERVES TO THE HEART
Ganglion cells of the sympathetic nervous system arise from neural crest cells (Moore and Persaud, 2008). Neural crest cells migrate from the body segments to penetrate the underlying somites and continue to the region of the future paravertebral.
AUTONOMIC NERVOUS SYSTEM
- ANATOMY OF THE SYMPATHETIC NERVOUS SYSTEM
- CERVICAL SYMPATHETIC CHAIN COURSE AND RELATIONS
- MIDDLE CERVICAL GANGLION (MCG)
- VERTEBRAL GANGLION
- INFERIOR CERVICAL GANGLION
- CERVICOTHORACIC GANGLION (CTG)
The remaining thoracic ganglia (apart from the two that have been mentioned and the last two or three) "rest against the head of the ribs and are posterior to the costal pleura" (Standring et al., 2008) [Figure 19]. Furthermore, variations exist regarding the position of the ganglia in the sympathetic trunk and their size” (Groen et al., 1987).
ADDITIONAL MEDIAL BRANCHES
In a study conducted by Groen et al. 1987), the number of thoracic sympathetic ganglia was found to vary between 8 and 10. Ganglia were found to be fused at various levels (ie sixth and seventh thoracic ganglia) in all their specimens (Groen et al., 1987). .
THE ANATOMY OF THE PARASYMPATHETIC NERVOUS SYSTEM TO THE HEART
The “pulmonary branches contain fibers that enter the ganglia of the pulmonary plexuses” (Standring et al., 2008). 47 to the first part of the subclavian artery, while on the left it arose from the vagus nerve on the left side of the aortic arch (Standring et al., 2008).
THE ANATOMY OF THE CARDIAC PLEXUSES
- DEEP CARDIAC PLEXUS
These bundled nerves coursed anteriorly or posteriorly to the arch of the aorta to the cardiac plexus (Gardner et al., 1975). The two parts of the cardiac plexus together send efferent fibers to "(1) atria directly, and to the rest of the heart through the coronary plexuses, and (2) to the lungs via the anterior surfaces of the pulmonary roots (anterior part of the pulmonary plexus)” (Romanes, 1968).
DESCRIPTION OF CARDIAC NERVES
- CARDIAC NERVES OF THE SYMPATHETIC CHAIN
- CARDIAC NERVES OF THE PARASYMPATHETIC NERVOUS SYSTEM
The left thoracic cardiac branches arise from the corresponding vertebral levels of the sympathetic trunk" and. The thoracic branches "join the cervicothoracic or thoracic cardiac branches of the sympathetic trunk before extending anteriorly toward the right bronchus” (Mizeres, 1972).
MATERIALS
The research was conducted in the aforementioned departments (in accordance with the Human Tissue Act 51 of 1989, and the National Health Act, 2003) with permission from the Biomedical Research and Ethics Committee of the University of KwaZulu-Natal (ethical clearance number: BF 152/07). Incidence of cervical ganglia (superior, middle, vertebral, and inferior or cervicothoracic) and their cardiac contributions.
METHODS
- CERVICAL DISSECTION
The lungs were removed by excision of the pulmonary vessels and bronchi at the hilum. The skin and fascia were reflected from medial to lateral to the second vertical incision.
NOMENCLATURE
- IDENTIFICATION OF THE CERVICAL SYMPATHETIC CHAIN
- CERVICAL GANGLIA
- MIDDLE CERVICAL GANGLION
The brachiocephalic trunk and subclavian artery on the right side were further dissected to view the ganglia and contributions to the cardiac plexus, while the common carotid artery and subclavian artery were further dissected on the left side to view the same. In this study, the superior cervical ganglion was described as the ganglion located posterior to the common carotid artery (Kawashima, 2005).
The middle cervical ganglion was described as the ganglion located in the CSC between the SCG and the ICG or CTG. The location and description of the MCG was based on Becker and Grunt's (1957) classification, which described the MCG in relation to the ITA, i.e.
- VERTEBRAL GANGLION
- INFERIOR CERVICAL GANGLION
- THORACIC SYMPATHETIC CHAIN
- CARDIAC PLEXUS
- SUPERFICIAL CARDIAC PLEXUS
- DEEP CARDIAC PLEXUS
- CERVICAL SYMPATHETIC CARDIAC NERVES
- SUPERIOR CERVICAL CARDIAC NERVE
- MIDDLE CERVICAL CARDIAC NERVE
- INFERIOR CERVICAL CARDIAC NERVE
- CERVICOTHORACIC CARDIAC NERVE
- THORACIC CARDIAC NERVES
- TCN 1
- TCN 3
- TCN 4
- TCN 5
- TCN 7
- TCN 8
- VAGUS NERVE
- CERVICAL VAGAL CARDIAC NERVES
- THORACIC VAGAL CARDIAC NERVES
- CERVICAL SYMPATHETIC CHAIN
- COURSE AND RELATIONS
- MIDDLE CERVICAL GANGLION
- OVERALL INCIDENCE OF THE MIDDLE CERVICAL GANGLION
The vertebral cardiac nerve is described as the nerve that exits the VG in any part of the cardiac plexus. The cervicothoracic cardiac nerve is described as the nerve arising from the CTG to reach any part of the cardiac plexus.
MCG lying on the ITA -„normal‟ MCG;
MCG lying below ITA -„low‟ MCG
VERTEBRAL GANGLION
The incidence of the VG between the fetal and adult specimens compared favorably. There were no differences between the incidence of ICG in either the fetal or adult specimens.
CERVICOTHORACIC GANGLION OVERALL INCIDENCE OF CTG
The location of the upper thoracic chain (up to the 6th thoracic vertebra) was on the neck of the ribs and their intermediate intercostal spaces. The thoracic chain (from the 7th thoracic vertebra) was close to the vertebral bodies and the intervening spaces.
THORACIC GANGLIA
The location and number of ganglia were examined to describe the medial contributions from this chain to the cardiac plexus. The deep cardiac plexus is located posterior to the aortic arch and anterior to the tracheal bifurcation in 100% of specimens.
SUPERFICIAL CARDIAC PLEXUS OVERALL INCIDENCE
The superficial cardiac plexus was located in the aortic arch and pulmonary artery in 80% of the specimens. The left SCP was found in relation to the aortic arch while the right SCP was in relation to the brachiocephalic trunk.
DEEP CARDIAC PLEXUS OVERALL INCIDENCE
DCP was found in association with bifurcation of the trachea and right pulmonary artery in 100% of these specimens. Key: ICCN-Inferior Cervical Cardiac Nerve, CTCN-Cervicothoracic Cardiac Nerve, MCCN-Middle Cervical Cardiac Nerve, SCCN-Superior Cervical Cardiac Nerve, VCN-Vertebral Cardiac Nerve.
- MIDDLE CERVICAL CARDIAC NERVE
Key: HMCG-middle cervical ganglion of high type, LMCG-middle cervical ganglion of low type, VG-vertebral ganglion, MCCN-middle cervical cardiac nerve, RLN-recurrent laryngeal nerve, I-inferior, L-lateral, M-medial,.
- VERTEBRAL CARDIAC NERVE (VCN)
Key: VCN-Vertebral Cardiac Nerve, VG-Vertebral Ganglion, VN-Vagus Nerve, SCG-Superior Cervical Ganglion, MCG-Middle Cervical Ganglion, ICG-Inferior Cervical Ganglion, DCP-Deep Cardiac Plexus, SCP-Superficial.
- INFERIOR CERVICAL CARDIAC NERVE (ICCN)
Legend: ICG-inferior cervical ganglion, ICCN-inferior cervical cardiac nerve, MCG-middle cervical ganglion, I-inferior, L-lateral, M-medial, S-superior.
- CERVICOTHORACIC CARDIAC NERVE (CTCN)
Key: DCTG-cervicothoracic ganglion, CTCN-cervicothoracic cardiac nerve, CN X-vagus nerve, I-inferior, L-lateral, M-medial, S-superior.
- First thoracic cardiac nerve (TCN 1)
A total of 36 thoracic-cardiac nerves originated from the T1 ganglion in the examined specimens [Plate 17 and Figure 53]. Key: ARCH-Arch of aorta, CN X-Vagus nerve, TCN1-First thoracic cardiac nerve, T2G-Second thoracic ganglion, T3G-Third thoracic ganglion, T4G-Fourth Thoracic ganglion, I-Inferior, L-M-Medial, L-M-Medial , S-Superior.
- Second thoracic cardiac nerve (TCN 2 ) OVERALL INCIDENCE OF TCN 2
Key: T2G-second thoracic ganglion, T3G-third thoracic ganglion, T4G-fourth thoracic ganglion, CN X-vagus nerve, TCN2-second thoracic cardiac nerve, I-inferior, M-medial, L-lateral, S-superior. In the 58 cases where TCN2 was absent, the medial branches terminated in the thoracic aorta in 20%.
A total of 17 thoracic-cardiac nerves originated from the T3 ganglion in the examined specimens [Plate 19 and Figure 55]. Key: TCN3-Third Thoracic Cardiac Nerve, T2G-Second Thoracic Ganglion, T3G-Third Thoracic Ganglion, T4G- Fourth Thoracic Ganglion, CN X-Vagus Nerve, I-Inferior, L-Lateral, M-Superior, S-Superior.
A total of 12 thoracic cardiac nerves originate from the T4 ganglion in the studied specimens [Table 20 and Figure 56]. Key: T2G-second thoracic ganglion, T3G-third thoracic ganglion, T4G-fourth thoracic ganglion, T5G-fifth thoracic ganglion, CN X-vagus nerve, TCN2-second thoracic ganglion, TCN3-third thoracic cardiac nerve, TCN4-F our
A total of 3 thoracic cardiac nerves originate from the T5 ganglion in the studied specimens [Table 21 and Figure 57]. TCN5 was present in 4% (3/80) of samples; these were found only on the right side of these specimens.
- Sixth thoracic cardiac nerve (TCN 6 ) OVERALL INCIDENCE OF TCN 6
- Seventh thoracic cardiac nerve (TCN 7 ) OVERALL INCIDENCE OF TCN 7
- Eighth thoracic cardiac nerve (TCN 8 ) OVERALL INCIDENCE OF TCN 8
- VAGUS NERVE
- CERVICAL VAGAL CARDIAC NERVES OVERALL INCIDENCE
- CERVICAL SYMPATHETIC CHAIN 1. COURSE AND RELATIONS
This study is consistent with Kalsey et al. 2000), in that no duplication of the CSC exists proximal to the SCG. This study disagrees with Axford (1928) and Standring et al. 2008), the MCG being occasionally replaced by small ganglia in the sympathetic trunk; this was not found in any of the samples in this study.
MCG lying above the ITA-‘high’ MCG;
The study is consistent with standard anatomical literature (Standring et al., 2008) in that the MCG is the smallest cervical ganglion. This study also confirms that the MCG is occasionally absent as reported by Standring et al.
MCG lying on the ITA-‘normal’ MCG;
Standard anatomical literature (Standring et al., 2008) describes this ganglion as the smallest of the three cervical ganglia or sometimes absent or replaced by small ganglia while Kalsey et al. 2000) describes the location of this ganglion as anterior or just superior to the ITA and states that it may be connected to the ICG. This confirmed the findings of Pick and Sheehan (1946) in that the MCG may have a double occurrence or be represented by a small nodule.
MCG lying below ITA-‘low’ MCG
VERTEBRAL GANGLION
This study agrees with Becker and Grunt (1957) in designating the fourth ganglion found on the CSC as "the vertebral ganglion" because of its close connection with the vertebral artery. 161 study also confirms reports by Mitchell (1953), Elias (2000) and Kawashima (2005) in that the intermediate ganglia should be referred to as the vertebral ganglion.
INFERIOR CERVICAL GANGLION
CERVICOTHORACIC GANGLION
162 of the second, third and fourth thoracic ganglia, confirming the reports of Pather et al. Kawashima (2005) and current standard anatomical textbooks (Standring et al., 2008) report that the CTG lies on or lateral to the lateral border of the longus colli muscle and posterior to the vertebral artery.
THORACIC SYMPATHETIC CHAIN 1 COURSE AND RELATIONS
- THORACIC GANGLIA
- ADDITIONAL MEDIAL BRANCHES
164 disagreed with the findings of Groen et al. 1986) who reported that the sixth and seventh ganglia were fused in all their specimens. In this study, the GSN had its highest origin from the fourth thoracic ganglion (T4G); this differed from standard anatomical literature (Cunningham, 1968; Standring et al., 2008) [T4G vs.
CARDIAC PLEXUS
- SUPERFICIAL CARDIAC PLEXUS
The deep part was located posterior to the aortic arch and anterior to the tracheal bifurcation in 100% of the specimens. Hollinshead (1974) and McMinn (1994) described the SCP as located between the arch of the aorta and the pulmonary trunk, to the right of ligamentum arteriosum and continuous with the deep cardiac plexus.
CERVICAL SYMPATHETIC CARDIAC NERVES
- SUPERIOR CERVICAL CARDIAC NERVE
- VERTEBRAL CARDIAC NERVE
- INFERIOR CERVICAL CARDIAC NERVE
In its course, the MCCN always passed posterior to the common carotid and anterior or posterior subclavian arteries, which compares favorably with reports by Kalsey et al. This study disagrees with Pather et al. 2006) in that the CTCN only contributed to the DCP, as this study also records CTCN contributing to the SCP in 4% of these samples.
THORACIC CARDIAC NERVES
- CERVICAL VAGAL CARDIAC NERVES
- THORACIC VAGAL CARDIAC NERVES
- RECURRENT LARYNGEAL CARDIAC NERVES
This study describes that these branches arise from the thoracic part of the vagus nerve, based on the description of Mitchell (1953). This study differs from the standard anatomical literature reviewed (Romanes, 1968; Hollinshead, 1974; Standring et al., 2008), as the RLN contributed 28 cardiac nerves to the DCP.
THORACIC SYMPATHETIC CHAIN
- SUPERFICIAL CARDIAC PLEXUS
- DEEP CARDIAC PLEXUS
This study also agrees with the standard anatomical literature regarding the location of the SCP. This study revealed that the cervical cardiac nerves innervated in their course in the cardiac plexuses.
CERVICAL CARDIAC NERVES
This study described an SCP related to the ascending aorta in 21% of our specimens, which is consistent with Mizeres (1972). Furthermore, this study differs from standard anatomical description of the contributions to the SCP and instead describes it as primarily formed by the inferior cervical vagal cardiac nerve and all cervical cardiac nerves.
THORACIC CARDIAC NERVES
CERVICAL VAGAL CARDIAC NERVES
- THORACIC VAGAL CARDIAC NERVES
- RECURRENT LARYNGEAL CARDIAC NERVES
